Filament and method of forming same



Feb. 24, 1970 J. FITTON 3,496,715

FILAMENT AND METHOD OF FORMING SAME Filed Feb. 25. 1968 fhluiapl Wid/Lu- United States Patent 3,496,715 FILAMENT AND METHOD OF FORMING SAMEJoseph Fitton, Great Howarth House, Wardle Road, Rochdale, Lancaster,England Filed Feb. 23, 1968, Ser. No. 707,736 Int. Cl. D02g 3/02, 1/00;D01d 5/22 US. Cl. 57140 13 Claims ABSTRACT OF THE DISCLOSURE BACKGROUNDOF THE INVENTION The present invention relates to filaments in general,and more particularly to the treatment of filaments. Still morespecifically, the present invention relates to a met-hod 'of treatingfilamentary material, and to a novel filamentary material obtained inaccordance with this method.

It is well known to crimp filaments and filamentary materials, whichlatter term designates yarns and similar multi-filament structures. Theterm filament will hereafter be employed to designate in its broadestaspect all conceivable interpretations, that is multi-filaments,monofilaments and the like.

Once having been crimped, a filament has a given crimp modulus whichterm is intended to be an indication of the ability of a crimpedfilament to recover its crimped configuration upon being stretched andreleased, and this term is related to the crimp rigidity of thefilament. Crimp rigidity is measured by extending the filament under aload sufiicient to straighten the filaments or filament so that thecrimp is removed, and thereupon allowing the filament to contract undera very much smaller load. The crimp rigidity is considered to be theamount of contraction expressed as a percentage of the fully extendedlength. In general terms, a yarn or filament having a high crimp modulusalso has a high crimp rigidity. It will be readily understood that formany applications thehighest obtainable crimp rigidity, and thereforethe highest obtainable crimp modulus, is desirable.

For this reason industry has long sought to devise a means forincreasing the crimp modulus of a crimped yarn. This, however,heretofore has encountered difiiculties.

SUMMARY OF THE INVENTION The present invention overcomes thesedifiiculties.

More particularly, the present invention provides a method of increasingthe crimp modulus of a filament.

Still more particularly, the present invention provides a method bywhich a crimped filament or crimped yarn having a given crimp modulus isprocessed to produce a crimped filament or crimped yarn having a highercrimp modulus.

The method in accordance with the present invention is relatively simpleand requires for its carrying out no substantial technologicalexpenditures, thus adding little if anything to the expense of makingthe filament or yarn.

In accordance with one feature of the invention I pro- Ice vide a methodof increasing the crimp modulus of a filament, which method includes thesteps of advancing an elongated filament of given cross section in apredetermined path, and crimping the filament to thereby obtain aplurality of longitudinally arrayed curved filament portions each ofwhich transversely extends of the longitudinal extension of thefilament. Thereupon, the filament portions are subjected to deformationof a magnitude requisite for obtaining at all points of each of thefilament portions a cross sectional configuration whose major dimensionis located in the plane of curvature of the respective filament portion.In other words, the filament is substantially flattened along itslongitudinal extension, but in such a way that the major dimension ofthe resulting cross-sectional configuration is located in the generalplane of curvature of each curved filament portion, that is each crimpedportion of the filament. It is this increased cross-sectional dimensionin the plane of curvature of the crimp to which in accordance with thepresent invention the higher crimp modulus of filaments treatedaccording to the present method is attributable, because this increasesthe resistance to and facilitates the recovery from straightening of thefilament under load.

The crimp in the yarn or filament may be latent crimp and may bedeveloped, for instance by heating, before the filament or yarn issubjected to such deformation.

The deformation itself may be carried out by suitable pressure-applyingmeans, such as pressure rollers which are in line contact with oneanother and between which the filament or yarn passes, While pressure isbeing applied the yarn may be heated, and such heating may occurupstream of the application of pressure or it may occur simultaneouslywith application of pressure, for instance by heating of thepressure-applying means. I have found it advantageous, in cases where amulti-filament structure such as a yarn is to be treated in accordancewith my method, to mechanically or electrostatically spread theindividual filaments of the structure in sheetlike fashion transverselyof the direction of movement of the structure prior to entry of thesefilaments into the pressure-applying means.

It is clear that my method may be carried out continuously, and that thecrimp can be applied in a suitable manner-if it is not already presentas a latent crimpsuch as by twist crimping or false twist crimping.

My invention also relates to a novel yarn produced in accordance withthe aforementioned method.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic illustrationshowing apparatus suitable for carrying out the method according to thepresent invention; and

FIG. 2 is a highly magnified stylized perspective view of a portion of afilament which has been treated in accordance with the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing indetail it will be seen that FIG. 1 shows a filamentary structure, whichhere is assumed to be a multi-filament yarn 10; which is advanced in thedirection toward the left-hand side of the drawing by means of a pair offeed rollers 11 which rotate in the direction indicated by the arrowsassociated therewith. Arranged downstream of the rollers 11 ispressure-applying means which here is illustrated as a pair of coactingpressure applying rollers 12. The rollers 11 rotate at a peripheralspeed which is greater than that of the rollers 12, which latter alsorotate in the direction of the curved arrows which are associated withthem, whereas the straight arrows indicate the direction in. which theyapply pressure towards one another. Rotating of the rollers 11 at aperipheral speed in excess of that of the rollers 12 results in anoverfeed of the yarn between the two sets of rollers 11 and 12. a i 7 Aheater 14 of suitable construction well known in the art is arrangedbetween the rollers 11 and 12 and in the illustrated embodiment servesto encourage development of the crimp in the yarn 10, which in thisinstance is assumed to possess a latent crimp; Of course, the yarn canaiso be twist crimped or false-twist erimped if it does not have latentcrimp character'istics. How the crimp comes about is of no consequencein accordance with the present invention; the important point is thatthe yarn be crimped prior to entering between the rollers 12.

Crimping of the yarn in whatever selected fashion of course results inthe production of a plurality of longitudinally arrayed curved filamentportions, that is a plurality of filament portions on each of thefilaments, with each of these portions beirig curved and extendingtransversely of the longitudinal extension of the respective filament.It is of course well knowri that the. crimps in the individual filamentsof a yarn such as the multi-filament yarn 16 illustrated in FIG. 1 willhave their planes of curvature disposed in substantially random manner.This is particularly true in the case of latent crimp which developsinto an actual crimped state; on being encour= aged by heating with theheater 14. 7

As the yarn 10 enters the nip of the pressure applying rollers 12 of theembodiment illustrated in FIG. 1 the individualfilaments' of the yarnwill twist so that the pianes of curvature of substantially all of thecrimpsof each of the filaments become aligned with the line of contactbetween the pressure rollers. It is in this condition that each of thecrimped filament portions passes through the nip between the presstirerollers 12. In so doing the cross section of each of the filaments isvaried. In other words, the cross section of each of the filaments isflattened with the result that downstream of the rollers 12 the majordimension of the cross-sectional configuration of each filament will liein the plane of curvature of the crimped portion at any point along thefilament. This is illustrated by way of an example in FIG: 2 which,however, is a highly stylized showing not intended to be representativeof the actual configuration, but only suggestive thereof. FIG. 2 shows ashort length of filament treated in accordance with the presentinvention and it will be seen that the cross section there is shown tobe substantially rectangular. It will, of course, be realized that theactual cross section of filament treated in accordance with the presentinvention will not be precisely of this shape, but will be rather moreof an elliptical section which may have slightly flattened sides. FIG. 2does, however, serve to suggest that the major dimension of the filamentcross section extends, once the filament has been treated in accordancewith the present invention, in the plane of curvature of the respectivecrimped portion, that is the plane of curvature of each crimp.

Also in accordance with the present invention I have found itadvantageous if the individual filaments of a multi-filament yarn suchas that shown in FIG. 1 are spread transversely of the direction of yarnadvancement in sheet-like fashion before they pass into the nip betweenthe pressure rollers 12 or whatever other pressureapplying means isbeing utilized. This will facilitate realignment of the individualfilaments so that the planes of curvature of substantially all thecrimps become aligned with the line of contact between the pressurerollers, as pointed out before. Such spreading can be effected eithermechanically or electrostatically in a manner which is well known in theart and need not therefore be described fiirther in detail.

on being processed in accordance with the present invention, the yarn10' is then taken up on a conventional take-up 15, as illustrated inFIG. 1. i

By treating a yarn in accordance with my novel method so that thegreatest cross-sectional dimension of each filament of the yarn at anypoint along the respective filament will lie in the plane of curvatureof the respective crimped portions of each filament, the crimpresistance to straightening of the individual filaments is considerablyincreased, and hence the crimp modulus of the yarn is also increased. Itis clear that this represents a significant advance in this field andprovides the type of special filament, or special yarn, which has longbeen sought in this industry but which heretofore has .notbeenavailable.

Yarn made from filaments treated in accordance with my presentinvention, and fabric made from such yarn, should not only haveparticularly good recovery characteristics from extension, but can alsobe expected to exhibit excellent flexibility and draping characteristicsas well as superior cover and opacity.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types offilamentary structures differing from the types described above;

While the invention has been illustrated and described as embodied in amethod for increasing the crimp modulus of a crimped filament, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired tobe protected by Letters Patent isset forth in the appended claims:

1. A method of processing a filament, comprising the steps of advancingin a predetermined path an elongated filament having a givencross-section and composed of a plurality of longitudinally arrayedcurved filament portions each of which extends transversely of thelongitudinai extension of said filament; and subjecting said filamentportions to deformation requisite for obtaining at all points of each ofsaid filament portions a cross-sectional configuration having its majordimension in the plane of curvature of the respective filament portion.

2. A method as defined in claim 1, wherein the step of subjecting saidfilament to deformation comprises engaging and subjecting each filamentportion to pressure from opposite sides of the plane of curvature of therespective portion.

3. A method as defined in claim 1, wherein the step of subjecting saidfilament to deformation comprises arranging two pressure-applyingsurfaces transversely of said path in line contact with one another,aligning the plane of curvature of each filament portion with the lineof contact between said surfaces, and advancing each filament betweensaid surfaces.

4. A method as defined in claim 1; and further comprising the step ofheating each filament portion while subjecting the same to saiddeformation.

5. A method as defined in claim 1; and further comprising the initialstep of crimping said filament preliminary to said step of subjectingthe filament to deformation, to thereby obtain said curved filamentportions.

6. A method as defined in claim 1, wherein said filament is possessed oflatent crimp; and wherein the step of crimping said filament comprisesdeveloping the latent crimp of said filament prior to deformation ofsaid filament portions.

7. A method as defined in claim 6, wherein the step of developing thelatent crimp in said filament comprises heating said filament.

8. A method as defined in claim 6, wherein the step of developing thelatent crimp of said filament comprises overfeeding said filament so asto permit the latent crimp thereof to develop.

9. A method as defined in claim 1, wherein the step of crimping saidfilament comprises false-twist crimping said filament.

10. A method as defined in claim 1, wherein all of said steps areperformed continuously.

11. A method as defined in claim 1; and further comprising the steps ofadvancing additional similar filaments in said predetermined pathsimultaneously with the firstmentioned filament; orienting the filamentportions of all of said filaments on entry of each portion into apredetermined increment of said path so that the plane of curvature ofeach curved filament portion at least temporarily coincides with a givenplane; and subjecting all of said filament portions to said deformationwhile their respective planes of curvature coincide with said givenplane.

12. A method as defined in claim 11; and further comprising the step ofspreading said filaments transversely of their direction of advancementin said path prior to subjecting said filament portions to saiddeformation.

13. As a novel article of manufacture, a yarn comprising a plurality ofelongated crimped filaments each of which includes a plurality oflongitudinally arrayed curved filament portions extending transverselyof the longitudinal extension of the respective filament, each of saidfilament portions having its major cross-sectional dimension in theplane of curvature of the respective filament portion.

References Cited UNITED STATES PATENTS 2,601,771 7/1952 Cameron.

3,065,519 11/1962 Starkie.

3,162,995 12/1964 Comer et a1. 57-140 XR 3,196,602 7/1965 Jenkins et al.57-34 XR 3,332,226 7/ 1967 Rosenstein 57-140 3,358,345 12/1967 Daniel28-12 3,404,522 10/ 1968 Stoll et a1. 57-34 3,412,192 11/1968 Clapson28-12 XR 3,421,193 1/1969 Taylor 28-7215 DONALD E. WATKINS, PrimaryExaminer US. Cl. X.R.

